In general, lithium-containing transition metal oxides are used for a positive electrode active material for lithium ion battery. In particular, they are lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), lithium manganite (LiMn2O4) and the like. A combination of the lithium-containing transition metal oxides is proceeding in order to improve properties such as high capacity, cycle characteristic, storage characteristic, decreased internal resistance, rate performance, and safety. Specifically, lithium ion batteries, for large-size equipment use such as automobile use and load leveling use, require properties different from those of mobile phone use and mobile computer use. In particular, high capacity and low resistance are required for automobile use and high capacity and long lifetime are required for load leveling use.
Traditionally, the positive electrode for lithium ion battery is produced in a manner such that positive electrode active material and conductive material are mixed in organic solvent where binder dissolves, paste thereof is formed, the paste is coated on an aluminum foil, and then drying operation and pressing operation are conducted. The binder is necessary for maintaining adhesion between the positive electrode active material, the conductive material and the aluminum foil (current collector). Further, the conductive material is mixed in order to provide conductive property with the positive electrode active material which is poor at conductive property.
For example, such positive electrodes for lithium ion battery are disclosed in Patent documents 1 to 3. In these active materials, the positive electrode for lithium ion battery disclosed in Patent document 1 is produced in a manner such that paste of positive electrode active material is coated on an aluminum foil for a current collector where hydration and oxidation treatments are conducted on a surface. Further, the positive electrode active material paste used here includes positive electrode active material, conductive material such as carbon black and graphite, binder such as PTFE and solvent such as water (paragraphs 0016 to 0025 in the specification of Patent document 1).
Further, Patent document 2 discloses a positive electrode for lithium ion battery of an aluminum foil comprising a film containing compounds having ion permeability and carbon particulates as a lower layer, and a film containing binder, carbon particulates and positive electrode active material as a upper layer (paragraph 0009 and the like in the specification of Patent document 2).
Further, a positive electrode for lithium ion battery disclosed in Patent document 3 is produced in a manner such that positive electrode active material composition is coated on Al alloy positive electrode current collector. The positive electrode active material composition used here is produced in a manner such that positive electrode active material, polyvinylidene fluoride binder and carbon conductive material are dispersed in a solvent of N-methyl pyrrolidone (paragraphs 0031 and 0032 and the like in the specification of Patent document 3).    (Patent document 1) Japanese Patent Application Publication No. 2008-103132    (Patent document 1) Japanese Patent Application Publication No. 2007-226969    (Patent document 1) Japanese Patent Application Publication No. 2005-243636